Hsal 2, A Novel Homeobox Gene in Hematopoiesis

描述（由申请人提供）： 该提案的长期目标是确定Hsal 2在骨髓生成中的作用。Hsal 2是最近发现的一个异源同源盒基因，与果蝇中的Sal同源盒基因具有序列同源性。Hsal家族成员的突变导致具有多器官发育缺陷的Townes-Brockes综合征。Hsal 2表达存在于大多数人组织中，包括造血组织。Hsal 2的转录调控受两个独立的启动子控制，这两个启动子都含有多个可能的骨髓造血调控基因的结合位点，包括Wilms' tumor suppression gene（WT 1）和retinoic acid receptor-alpha（RAR）;（2）WT 1抑制荧光素酶报告基因系统中的Hsal 2启动子活性，而视黄酸（RA）激活Hsal 2表达;（3）Hsal 2表达与髓系定型一致;（4）Hsal 2缺失小鼠中的髓系群体显著减少。因此，我推测细胞内WT 1/RAR-α/Hsal 2通路可能在正常造血中起作用。Hsal 2在骨髓生成中的生物学功能将通过Hsal 2同种型在体外造血干细胞、骨髓细胞系和四环素诱导的胚胎干细胞中的过表达以及Hsal 2缺失小鼠的体内表征来研究。我们将继续表征Hsal 2的转录调控，重点是鉴定WT 1和RAR-α的结合位点。WT 1和RAR-α对Hsal 2表达的拮抗作用将通过在骨髓细胞系中过表达WT 1来进一步探索。这些研究所获得的知识将有助于更好地理解正常造血的关键途径，并有助于开发新的策略来对抗白血病。候选人Li Chai博士将在申办者Diane Krause博士和咨询委员会的指导下进行实验室研究。此外，这项建议的另一个目的是作为一种工具，将候选人培养成为造血和白血病领域的独立和富有成效的调查员。

DESCRIPTION (provided by applicant): The long-term goal of this proposal is to define the role of Hsal2 in myelopoiesis. Hsal2 is a recently identified divergent homeobox gene that has sequence homology to the Sal homeobox gene in Drosophila. Mutations of Hsal family member lead to Townes-Brockes syndrome with multiple organ developmental defects. Hsal2 expression is present in most human tissues including hematopoietic tissues. Several lines of evidence suggest that Hsal2 may be involved in myelopoiesis: (1) The transcriptional regulation of Hsal2 is controlled by two independent promoters and both promoters bear multiple putative binding sites for regulatory genes critical for myelopoiesis, including Wilms' tumor suppression gene (WT 1) and retinoic acid receptor-alpha (RAR); (2) WT 1 represses both Hsal2 promoter activities while retinoic acid (RA) activates Hsal2 expression in a luciferase reporter gene system; (3) Hsal2 expression coincides with the myeloid lineage commitment; (4) The myeloid population in Hsal2-null mice is significant reduced. Therefore, I hypothesize that an intracellular WT 1/RAR-a/Hsal2 pathway may play a role in normal hematopoiesis. The biological function of Hsal2 in myelopoiesis will be studied by overexpression of Hsal2 isoforms in hematopoietic stem cells, myeloid cell lines, and tetracycline-inducible embryonic stem cells in vitro, and characterization of Hsal2-null mice in vivo. We will continue to characterize the transcriptional regulation of Hsal2 with a focus on identification of the binding sites of WT1 and RAR-alpha. The antagonistic effect between WT1 and RAR-alpha on Hsal2 expression will be further explored by overexpression of WT1 in myeloid cell lines. The knowledge gained by these studies will contribute to better understanding of pathways critical for normal hematopoiesis and help to develop novel strategies to combat leukemia. The candidate, Dr. Li Chai will conduct the laboratory research under the guidance of a sponsor, Dr. Diane Krause, and an advisory committee. In addition, a further objective of this proposal is to serve as a vehicle for the development of the candidate into an independent and productive investigator in the area of hematopoiesis and leukemogenesis.